Catheter-based procedures are on the rise. Many procedures that used to require major surgery can now be performed with minimal invasiveness by means of a catheter which can be inserted into the patient's body through a tiny incision no more than two to three inches long typically in the leg. Catheter-based procedures conducted on the heart may include balloon angioplasty, coronary angiogram, atherectomy, transmyocardial revascularization (TMR), percutaneous balloon valvoplasty, ablation and heart valve replacement
A more recently developed catheterization procedure is renal denervation (RDN). It is a minimally invasive, endovascular catheter-based procedure using radiofrequency ablation aimed at treating resistant hypertension. Resistant hypertension is a common clinical problem faced by both primary care clinicians and specialists. As older age and obesity are two of the strongest risk factors for uncontrolled hypertension, the incidence of resistant hypertension will likely increase as the population becomes more elderly and heavier.
As one of the three major parts of the autonomic nervous system, the sympathetic system fuels the release of certain hormones that affect and control blood pressure. In hypertension, the continued release of low-dose amounts of these hormones can increase blood pressure. Hypertension can be controlled by diet, exercise and drugs. However, resistant hypertension (commonly defined as blood pressure that remains above goal in spite of concurrent use of three antihypertensive agents of different classes) requires more aggressive treatments, including surgery. It has been established that severing the renal nerves improves blood pressure. However, this procedure involves surgery and all its attendant risks, and may result in global sympathetic denervation below the chest.
Being able to de-nervate, or silence, only the renal nerves through a catheter-based system is a crucial development. A small catheter is placed in the femoral artery and access to the nerves is gained through the renal artery. By passing an energy source into the renal artery and transmitting a low-dose energy, radiofrequency ablation, through the catheter, inbound and exiting renal sympathetic nerves are impaired or “denerved” at selected locations along their lengths. This causes reduction of renal sympathetic afferent and efferent activity and blood pressure can be decreased. However, the renal nerves are embedded in the casings or layers around the renal arteries and may not be readily accessed by a catheter ablating from within the renal artery.
Accordingly, there is a desire for an ablation catheter that can penetrate inner layers of the renal artery to reach the nerves in the outer layers of the renal artery.